Automobiles and other transportation vehicles have typically included a cigarette lighter receptacle that can be used to supply power to accessory device. Some of the accessory devices that can be connected to the cigarette lighter receptacle include radios, cellular telephones, notebook computers, DC to AC inverters, etc.
More recently, automobile manufacturers started adding additional cigarette lighter sockets and labeled them “Accessory Power”. These receptacles are switched off when the key to the vehicle is not in an “Accessory” or “ON” position. This alleviates the problem of battery drain that can occur when an occupant of the vehicle plugs a device into the receptacle and then removes the keys and leaves the vehicle. Without a switchable “Accessory Power” receptacle, the receptacle would continue to supply power allowing an accessory device to drain the vehicle battery. Although, the “Accessory Power” receptacle solves the battery problem with some newer vehicles, there are many older vehicles on the road and still new vehicles that don't disable the power to the receptacles.